This invention relates to attaching plastic liners, particularly but not only ultrahigh molecular weight polymers, to substrates. Such liners are often used, for example, to line hoppers, railroad car and truck bodies, and ship holds used for coal and other materials. UHMW liners are particularly desirable because the material provides flexibility and slipperiness with very high abrasion, impact and chemical resistance. Such materials can outwear steel in many applications, and the slipperiness of the material prevents the coal or other material from sticking or freezing to the substrate.
Such liners are, however, difficult to attach securely to the substrate. One particular problem in this regard is that the liner materials exhibit a relatively high degree of linear thermal expansion and contraction, and for this and other reasons glues and some other conventional arrangements are not suitable. The expansion and contraction problem can be solved by the known expedient of using bolts that extend through oversized holes in the substrate to allow lateral movement, but this can make the bolt difficult to attach.
It is also desirable and known to cap attachment bolts with plastic and make them flush with the liner surface to provide surface continuity for improved smoothness and wear. The closest known prior approach of this type involves using a frusto-conical bolt head that fits in a mating recess on the liner surface, but this is not totally satisfactory from the standpoints of holding the bolt against rotation, particularly while a nut is being attached, providing an adequate seal between the bolt head and the recess, allowing field installation using conventional tools, simplicity of manufacture, and general adaptability to various applications.